18/21 pikeman. Do it, it's a pretty interesting and different playstyle.
Mechanized infantry aka 24/15 cavalry with heavy armour and a heavy horse. Supporting your infantry by constantly slow speed harassment of the enemy melee blob. Hit and run arabian cav is for women. Pretty good for winning rounds.
Goedendag shielder, it is pretty damn cool to do 1h animations with a 117 length weapon. Damage is weak, but it works, not sure what the best build is though.
Throwing lance hoplite is a brilliant build.
Those are my ideas for builds that are fun to play but also reasonably effective, in case you are not exclusively looking for complete gimmick builds